Objectives: 1. The objective of this work is to develop a more precise understanding of the nature and organization of controlling elements in the lac operon of Escherichia coli by both genetic and in vitro biochemical studies. 2. In the current year, we hope to isolate and characterize deletions mutants which remove the entire lac promoter region. These will be used as important controls in the study of the binding of RNA polymerase to the lac promoter region. We will characterize a larger number of trp-lac fusion strains in which different segments of the lac promoter have been removed. We will characterize mutants of E. coli in which 3'5'-cyclic-GMP synthesis has been altered in order to determine the role of this nucleotide. Bibliographic references: Mitchell, D., Reznikoff, W., Beckwith, J. Genetic fusions defining trp and lac regulatory elements. J. Mol. Biol. 93:331-350 (1975); Sabourin , D. and Beckwith, J. Deletion of the Eschericha coli gene crp. J. Bacteriol. 122:338-340 (1975).